A heat pump maintains a dwelling at 68 F. When operating steadily, the power input to the heat pump is 5 hp, and the heat pump receives energy by heat transfer from 55 F well water at a rate of 500 Btu/min. determine the coefficient of performace. Evaluating electricity at $ 0.10 per kW.h determine the cost in a a month when the heat pump operates for 300 hours.